In the first season of Penny Dreadful, there was an episode called "Séance." Which was extremely creepy if you ask me because the name of the episode referred to the calling session they performed during a party.
During the episode "Séance" in season one, when Evelyn Poole donned her guise of Madame Kali and called the spirits, she referred to Vanessa as Amunet.
In Ancient Egypt, the West is the where the dead enter the underworld and Amunet is believed to be as the goddess who welcomes their entrance into the Kingdom of Osiris. She is believed to be the female form of the greater god Amun Ra and is one of the eight featured deities in the Ogdoad.
For many believers, Amun-Ra created himself. He was the ultimate creator.
Over the years, she became increasingly associated with Iusaaset, a shadow of Atum. This association made her the mother of all creation who owns the tree from which life emerged.
It was implied that even Ferdinand believes that Vanessa is the reincarnation of the goddess because after he told Sir Malcolm Murray about the prophecy, he warned him to keep it from his ward.
Vanessa was a natural-born witch, not a healer like Joan Clayton (Cut-Wife). Joan also revealed Vanessa is a very powerful witch.
Considering Vanessa's sigil is a scorpio, in ancient Egyptian mythology, there is a goddess named Serket who is often portrayed with a scorpion on the top of her head. She is an advisor to Isis, the Queen of Heaven and helps the other gods fight evil as well.
Meanwhile, Amunet is the consort of the god Amun-Ra, and is one of eight deities who helped to create the world.
If Amunet is an evil character in PD mythology, it is possible that executive producer John Logan might have taken liberties with merging two goddesses into same person. Vanessa's sigil could be a nod to her past life as Amunet.
Same assumption works for why Verbis Diablo went after Vanessa to hunt her. Amun-Ra introduced himself as Satan to lure them into his own mission, getting his bride Amunet, back.
Note: Please consider all the characters in the show and their previous appereances in folklore and literature. Every character (including Dracula and Mina) has a background in our universe either in folklore and myhtology or literature. From Dorian Grey to Victor Frankenstein. It is natural that we assume things based on what we know.